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Tests and treatment for chronic myelomonocytic leukaemia (CMML)

Many people are diagnosed with CMML because doctors find abnormal monocytes during a blood test for something else. Your doctor may then arrange a number of tests for you, including:

  • blood tests to look at how many blood cells you have and whether they are normal
  • a bone marrow test

Your doctor may also do tests to look for anything unusual in the chromosomes Open a glossary itemof the CMML cells. Chromosomes contain the genetic material inside cells. These tests are called cytogenetics (pronounced sigh-toe gen-et-ics).

Treatment for CMML

The type of treatment you need depends on:

  • the type of CMML you have
  • whether you have symptoms
  • your age
  • whether you have any other medical conditions

Watchful waiting

If you have no or few symptoms you might not need treatment at first. Instead you will have regular check ups including blood tests. This is called watchful waiting.

Supportive treatment

The aim of supportive treatment is to:

  • reduce the number of blast cells
  • improve your symptoms
  • improve your quality of life
  • delay a possible transformation of acute myeloid leukaemia

Donor stem cell transplant

The only way to cure CMML is to have a donor stem cell transplant. This is an intensive treatment and it has risks. This is why it’s unfortunately not suitable for everyone.

Supportive treatment

Most people need supportive treatment at some point. The treatment you need depends on the type of symptoms you have. You might need a combination of treatments.

Blood and platelet transfusions

You might have blood transfusions if your red blood cells are low. And if your platelets are low you will have a drip of a clear fluid containing platelets.

Having a lot of blood transfusions can cause a build up of iron in your body. Red blood cells contain iron and your body stores this. But too much iron in your body can damage your heart and liver. To stop this, you might need to take medicines to get rid of the extra iron.

Growth factors

Growth factors are drugs that encourage your bone marrow to make more blood cells. We know from research that this can reduce the number of blood transfusions that people need.

Erythropoetin is a growth factor that increases the number of red blood cells. So, you might have this if your red blood cell level is low. 

G-CSF is a growth factor that increases the number of white blood cells. So, you may have this if your white blood cell levels are low.

You have both of these drugs as injections just under the skin (subcutaneously).


You might also need to take antibiotics to treat infections.

Chemotherapy for CMML

Chemotherapy uses cell killing (cytotoxic) drugs to destroy the abnormal cells.

The drugs work by disrupting the growth of cells and stopping them from dividing. You can have chemotherapy as a tablet, an injection just under your skin, or as an injection into a vein. You might have just one drug or a combination of drugs.

The type of chemotherapy you have depends on your type of CMML and your general health. If you have just been diagnosed your first chemotherapy is likely to be cytarabine, hydroxyurea or azacitidine.

If you are at high risk of developing AML, you might have chemotherapy similar to that used to treat AML.

Donor stem cell transplant

Donor stem cell transplants are usually only suitable for people who:

  • are younger
  • are in reasonably good health, apart from your CMML
  • have a suitable donor (sibling or unrelated)

This is because it’s an intensive treatment and there are risks. There are several stages to a donor stem cell transplant.

Stages of a donor stem cell transplant

You have a stem cell transplant after very high doses of chemotherapy. You might have targeted drugs with the chemotherapy. You may also have radiotherapy to your whole body. This is called total body irradiation or TBI.

After this treatment you have stem cells from a donor to replace your own bone marrow cells. You have these through a drip into your bloodstream.

To be able to have intensive treatment you need a stem cell donor. The donor is someone whose stem cells match yours. The most suitable donor is usually a close relative such as a brother or sister. If you don't have a suitable family donor your doctor might look for an unrelated donor for you.

It takes from a few days to a few weeks for the donor stem cells to start making new blood cells. During this time, you will need blood and platelet transfusions. You are also at a high risk of developing infections, so you have antibiotics and anti viral drugs to try to prevent this from happening.


Researchers around the world are looking at better ways to treat myeloproliferative or myelodysplastic disorders and manage treatment side effects.These clinical trials sometimes include people who have CMML.

A study is setting up a record or ‘registry’ of information about a large number of people across Europe with blood cancers including CMML. If you take part, the team will collect information about your medical history, test results and treatments. Doctors also want to find out as much as possible about the many different types of myelodysplastic or myeloproliferative disorders and how best to treat them.

Cancer Research UK Clinical Trials Database

You can find a clinical trial looking at CMML on our clinical trials database. Click on the ‘recruiting’, ‘closed’ and ‘results’ tabs to make sure you see all the trials.

You need to talk to your specialist if there are any trials that you think you might be able to take part in.

Coping with CMML

Coping with a rare condition can be difficult, both practically and emotionally. Being well informed about your condition and its treatment can help you to make decisions and cope with what happens.

Information and help